The present invention relates to a method and apparatus for facilitating the connection of tubular used in the oil and gas exploration and extraction industries. More specifically, the invention relates to an apparatus for running or pulling tubular into or out of a well bore.
In the construction of oil or gas wells it is usually necessary to line the well bore with a string of steel pipes commonly known as tubular or tubing or generically as oil country tubular goods (“OCTG”). For purposes of this application, such steel pipes shall hereinafter be referred to as “tubular OCTG”. Because of the length of the tubular OCTG required, individual sections of tubular OCTG are typically progressively added to the string as it is lowered into a well from a drilling rig or platform. The section to be added is restrained from falling into the well by some tubular engagement means, typically a spider or the like, and is lowered into the well to position the threaded pin of the tubular OCTG section adjacent the threaded box of the tubular OCTG in the well bore. The sections are then joined by relative rotation of the sections until such time as the desired total length has been achieved.
It is common practice to use a power tong to torque the connection to a predetermined torque in order to connect the sections of tubular OCTG. This traditional method and equipment types have been used extensively around the world for a period in excess of fifty years. While this method is in daily use it normally requires a large team of specialist personnel along with a plethora of equipment to successfully undertake this task. It is also a very dangerous task with personnel having to be located on a small platform suspended up to 15 feet from the rotary table and the power tong tethered to a steel cable under high loads.
In more recent times, a top drive may be used; this is, a top drive rotational system used for drilling purposes. Where a top drive system is used to make the connection, the use of a surface mounted slip type spider to restrain the section of tubular OCTG to be added may be problematic, due to the configuration of the spider in so much as it sits on or protrudes above the rig floor causing a further obstruction or safety hazard. It is therefore known to make use of an apparatus generically as referred to as an “FMS” or flush mounted spider, which can be inserted into the rotary table so that a section of tabular OCTG may be added or removed, and engaged therewith to hold the section in place. Such apparatus may comprise one or more slips and or toothed grapples, which may be hydraulically or pneumatically operated to engage an outer surface of the tubular. While this is advancement over the traditional approach as it lowers the equipment operational height; it has drawbacks in that because of the design characteristics of the upper section, plates, slips and or grapples may function or operate above the rotary table, thereby becoming a safety or operational problem. This method also places the tubular OCTG to be connected at a height that may still require an additional work table or platform to facilitate the connection thereof.
Secondly as the slips and or grapples tend to be functioned using only two pneumatic or hydraulic cylinders mounted to a horseshoe or split ring whereby side loading of the tools can occur if misalignment is an issue thereby scarring can occur to the outside surface of the tubular OCTG and its integrity thereof.
The intention of the present invention is to offer a much-improved method for an FMS for running tubular OCTG into a borehole without the shortfalls in the tools available today.